It is called denatonium benzoate , although it is known commercially as Bitrex . It was invented half a century ago and is used as an additive in highly toxic products to prevent accidental poisoning of humans (especially children) and domestic animals. It is present, for example, in bathroom cleaning products , in shampoo and soap , in antifreezes … It is also added to special polishes applied to the nails to combat the bad habit of biting nails ( onychophagia).
A curious detail is that the first use of Bitrex was as a flavor aversive in a cream to prevent tail bites between pigs .
